1. Field of the Invention
The present invention relates to digital radiography apparatus, and in particular, to apparatus such as digital subtraction angiography apparatus (hereinafter abbreviated to "DSA apparatus"), used in angiography, cardiography, or the like, for radiographing of subjects such as the heart, the aorta, or the like, moved by heartbeats or the like.
2. Description of the Prior Art
In radiographing by DSA apparatus, even slight motion of a subject may form a motion-artifact so as to greatly deteriorate the quality of an image. Therefore, conventionally, in radiographing a rapidly moving heart, images for about one stroke were averaged to make a masking image so as to reduce motion-artifacts.
However, the method provided no essential solution for the problem. Although the images according to the method have been used to obtain a moving picture in practice, subjects such as a coronary artery and the like could not be represented without using risky means such as selective angiography, or the like.